boiler with water softener

[stevewilliams]

Just want to check something - my dad has just been told that his header tank has to be isolated from his new condensing boiler because the salts in his water softener will damage the boiler. The header has been filled separately with hard water.

This leaves me with a few questions:

If his header tank runs dry because of a leak somewhere is there a safety cutout on the boiler?

He has no way of checking or topping up the header tank except by crawling around in the loft (he is in his 70s) - is this not unusual to leave a tank unconnected to the water supply?

Why could the plumber have not cut in before the softener to provide an untainted supply?

Water softeners provide drinking water - are they really that significant in emitting contaminating salts?

Steve

 

[Moss5]

I have operated a combi boiler on softened water for ten years and a combined oil fired/solid fuel system for 18 years.

The main point for you to consider is the effect on warranty cover.
If the boiler manufacturer excludes softened water, you may want to comply. Read the installation instructions, or contact the manufacturer directly.

Surely the warranty would be void without a water supply to make-up evaporation.

The installer could have broken-in to the hard-water supply to provide a dedicated supply to the feed & expansion tank. There is usually a 'hard' tap provided at the kitchen sink.

If the installer has been paid, you may have a fight on your hands.

 

[croydoncorgi]

The only serious objection to softened water is to its use in the primary circuit of the boiler (ie. the part including the rads, coil in HW cylinder). there's NO problem putting softened (or already-soft) water through the hot water heat exchanger of a combi boiler.

As I understand it, the main objection is to chloride ions getting into the primary water and causing corrosion. A common source of chloride is soldering flux not removed by flushing after installation. In priciple, a properly adjusted softener will NOT release chloride into the water - although salt IS used to regenerate the softener resin, it SHOULD all be flushed out as part of the regeneration cycle. What WILL be released into the water will be sodium ions (in exchange for the calcium that causes hardness - that's the way the permutit process works).

What I don't know is whether sodium in the water is regarded as a Bad Thing in itself and whether the residual chloride that will be present is really enough to be harmful to a heating system. (The objection to DRINKING softened water is that it's supposed to increase risk of heart disease, as well as tasting nasty.)

 

[lor]

we are not talking about combi boilers but condensing!
If the manuf says dont use soft water it is for a good reson, aluminium heat exchangers can be corroded by soft water. youshould not drinkartifically softened water.

 

[croydoncorgi]

OK - it's unlikely to find a condensing combi with a header tank - but not impossible.

and I still want to know whether it's sodium or chloride ions that damage HX's (theoretically or actually!)

 

[chrishutt]

I'm pretty sure than it's the chloride ions that are damaging, but ChrisR knows about these things.

 

[stevewilliams]

Cheers for your thoughts on that - I will check the boiler warranty for the details

Steve

 

[stevewilliams]

we are not talking about combi boilers but condensing!
If the manuf says dont use soft water it is for a good reson, aluminium heat exchangers can be corroded by soft water. youshould not drinkartifically softened water.

Really - you should not drink artificially softened water?

Steve